1. Field of the Invention
The present invention relates to a zigzag sewing machine in which a trimming device is removably disposed at a predetermined position on a machine bed, the marginal edge of a work fabric is trimmed by this trimming device and an overedge seam is formed along and over the trimmed edge.
2. Description of the Prior Art
A trimming device removably mounted on a bed of a zigzag sewing machine having a laterally joggable needle for forming zigzag stitches of variable stitch width to trim the marginal edge of a work fabric prior to overedge stitching has already been known. In a zigzag sewing machine provided with such trimming device on performing overedge stitching, the field position of the needle oscillation should be set so that formed zigzag stitches are placed along the marginal edge of the trimmed work fabric. When this setting operation is neglected, the zigzag stitches of any stitch width are not often placed along and over the trimmed marginal edge of the work fabric, and so, an overedge seam for overcasting the trimmed marginal edge is not formed.
A known trimming device for a zigzag sewing machine is constructed so that the attaching position thereof to a sewing needle can be adjusted. However, various limitations are imposed on this adjustment of the attachment position because of the structure of the sewing machine and this adjustment is troublesome for an operator. Accordingly, such trimming device is not suitably used for ordinary household zigzag sewing machines.